Prior etching machines use one of two techniques. The first technique employs a stationary blast unit, and the operator must rock the material to be etched, such as a glass plate, back and forth in the path of the grit guns. The second technique utilizes a blast unit in which all the grit guns are movable as a whole. These techniques have not proven satisfactory; both are unreliable and do not provide precision control of the etching process. The first introduces human error into the etching process, while the second requires precise mechanical motion control for the blast unit. Moreover, using conventional etching machines, it is not possible to adjust the individual grit guns relative to the material to be etched.